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Russell May
Russell May,
Japanese knotweed: a landmark decision in a deep-rooted battle
17 July 2018

The ruling in the recent Court of Appeal case of Network Rail Infrastructure Ltd v Williams and another concerning Japanese knotweed will have a huge impact on both homeowners whose properties are encroached by the invasive plant, and landowners who allow the plant to grow on their land and who fail to take reasonable steps to prevent such encroachment.


Claims were brought in private nuisance by the owners of two adjoining properties, which backed directly onto land owned by Network Rail. Japanese knotweed (described as a “pernicious” weed, the presence of which can cause physical damage to buildings) had been present on Network Rail’s land for at least 50 years and was encroaching on the properties. The basis for the claims was that the Japanese knotweed had caused damage to both properties and injunctions were therefore sought to compel Network Rail to eliminate the knotweed, as well as to pay damages.

The Recorder at first instance rejected the claimants’ submissions that encroachment without physical damage to the properties was an actionable nuisance, but still held in favour of the claimants on the basis that the presence of the knotweed diminished the value of their properties. Damages were also awarded in respect of that diminution.

Network Rail appealed the decision, firstly challenging the Recorder’s finding that the diminution in the value of property (pure economic loss) constituted an actionable private nuisance and secondly arguing that the damages awarded in relation to the residual diminution in market value of the properties, of £10,000 and £10,500 respectively, had been calculated incorrectly.

The appeal

Giving the leading judgment, Sir Terence Etherton MR upheld the county court decision but disagreed with the Recorder’s reasoning, finding that it was wrong in principle. He stated that the purpose of the tort of nuisance was to protect a landowner’s use and quiet enjoyment of their land, not to protect the value of property. The appeal was therefore upheld but on the basis that the encroachment of the knotweed had adversely affected the ability of the claimants to enjoy and use their land. He rejected the second ground of appeal believing that it was misconceived.

In his judgment, the general principles governing the cause of action of private nuisance were helpfully summarised, obviating the need to refer to other historic cases for guidance on the issue:

  1. A private nuisance is a violation of rights; it therefore must involve an interference with either a landowner’s legal rights, including a legal interest in land, or the amenity of the land.
  2. Though nuisance is often grouped into three categories (encroachment, interference and physical injury), these are mere examples and not a comprehensive list.
  3. The idea that physical damage is a requirement to establish nuisance should be treated with caution, as demonstrated by the facts of this case.
  4. Nuisance can be established by inaction or omission as well as by positive activity.
  5. The fundamental principle will always be reasonableness between neighbours.


Some landowners have historically taken a rather slack approach to protecting adjoining properties from the physical damage and the risk of future damage (such as the ability to develop land) caused by the presence of Japanese knotweed on their land. This recent decision sends out a clear message that this apathetic approach will no longer be tolerated, which should result in such landowners taking appropriate action to ensure that any Japanese knotweed on their land is effectively treated and not left to spiral out of control, blighting neighbouring properties.

Consistent with our policy when giving comment and advice on a non-specific basis, we cannot assume legal responsibility for the accuracy of any particular statement. In the case of specific problems we recommend that professional advice be sought.

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